Fix crashing on missing beatmaps

Author: Syriiin

Difficalcy.Tests/DummyCalculatorServiceTest.cs

@@ -45,7 +45,7 @@ protected override DummyCalculation CalculatePerformance(DummyScore score, objec
     protected override object DeserialiseDifficultyAttributes(string difficultyAttributesJson) =>
         double.Parse(difficultyAttributesJson);
 
-    protected override Task<bool> EnsureBeatmap(string beatmapId) =>
+    protected override Task EnsureBeatmap(string beatmapId) =>
         Task.FromResult(true);
 }
 

Difficalcy/Services/IBeatmapProvider.cs

@@ -5,7 +5,7 @@ namespace Difficalcy.Services
 {
     public interface IBeatmapProvider
     {
-        public Task<bool> EnsureBeatmap(string beatmapId);
+        public Task EnsureBeatmap(string beatmapId);
 
         public Stream GetBeatmapStream(string beatmapId);
     }

Difficalcy/Services/TestBeatmapProvider.cs

@@ -7,7 +7,7 @@ namespace Difficalcy.Services
 {
     public class TestBeatmapProvider(string resourceAssemblyName) : IBeatmapProvider
     {
-        public Task<bool> EnsureBeatmap(string beatmapId)
+        public Task EnsureBeatmap(string beatmapId)
         {
             var resourceName = $"{resourceAssemblyName}.Resources.{beatmapId}";
             var info = ResourceAssembly.GetManifestResourceInfo(resourceName);

Difficalcy/Services/WebBeatmapProvider.cs

@@ -1,6 +1,7 @@
 using System.IO;
 using System.Net.Http;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Configuration;
 
 namespace Difficalcy.Services
@@ -10,21 +11,21 @@ public class WebBeatmapProvider(IConfiguration configuration) : IBeatmapProvider
         private readonly string _beatmapDirectory = configuration["BEATMAP_DIRECTORY"];
         private readonly HttpClient _httpClient = new();
 
-        public async Task<bool> EnsureBeatmap(string beatmapId)
+        public async Task EnsureBeatmap(string beatmapId)
         {
             var beatmapPath = GetBeatmapPath(beatmapId);
             if (!File.Exists(beatmapPath))
             {
                 using var response = await _httpClient.GetAsync($"https://osu.ppy.sh/osu/{beatmapId}");
                 if (!response.IsSuccessStatusCode)
-                {
-                    return false;
-                }
+                    throw new BadHttpRequestException("Beatmap not found");
 
                 using var fs = new FileStream(beatmapPath, FileMode.CreateNew);
+                if (fs.Length == 0)
+                    throw new BadHttpRequestException("Beatmap not found");
+
                 await response.Content.CopyToAsync(fs);
             }
-            return true;
         }
 
         public Stream GetBeatmapStream(string beatmapId)